Method and composition for dispersing of pitch



3,102,065 METHOD AND CQlViPOSlTlON FQR DISPERSWG OF PITCH John F.Thurlow, Gorham, Maine, assignor to Virginia Chemicals & SmcltingCompany, a corporation of Maine t No Drawing. Filed Mar. 22, 1961, Ser.No. 97,468 11 Claims. (Cl. 162 175} The present application is directedto a method and composition for dispersing of pitch from pulp and paperin mill operations.

Pitch is normally considered as deriving from pine and other pitchywoods; however, pitch occurs also inhardwood mill operations. To thepaper make pitch is a dark brown or black deposit which he finds aroundthe edges of his heaters and chests, clogging his Fourdrinier wires,accumulating on his press rolls, and clogging or appearing as darkspecks in the finished sheet of paper. In both pulp and paper mills theoccurrence of pitch depends upon the kind of pulp used, as well as manyadditional factors which are detailed below.

A mill which cooks by the sulfite process or which manufacturesgroundwood may very easily have a pitch problem; the same applies if amill purchases either of these pulps. Mills using a semi-chemical orpartial cook process, usually sulfite, followed by mechanicaldisintegration-may have pitch problems, but other mitigating conditionsin the manufacturing process sometimes make these pitch problemsrelatively minor. The sulfite process is acid and, therefore, not assuccessful in removing pitchy materials as the alkaline processes. Thegroundwood process uses no cook at all and, consequently, removes onlythose constituents which are freed in finely divided form during thegrinding operation.

According to the present invention a composition containing watersoluble cationic starch, glycerol monostearate and a non-ionic surfaceactive agent, such as nonylphenol polyethlene glycol ether, alkyl phenolpolyethylene glycol ether (iso-octyl) or the like and deodorizedkerosene is added to the moving pulp in advance of individual troublepoints where the pitch has agglomerated. This composition also assurescomplete dispersion in the pulp slurry or in hot water of the cationicstarch which ordinarily does not perform well when used by itself. The

composition thus facilitates use of water soluble cationic starchwithout cooking. Furthermore, the composition retains unagglomeratedpitch particles in the sheet paper which particles are conventionallytoo minute to be detected easily by the naked eye. Thus, by continuouslyremoving pitch from the system there is prevented a buildup of pitch inthe paper making machinery. Conventional dispersants merely keep thepitch dispersed, but do not assist in purging the mill system and inconsequence build up may occur.

Accordingly, it is an object of invention to provide a pitch dispersingcomposition for use in pulp and paper mill systems.

Another object of invention is to provide a pitch dispersing compositionwhich enhances dispersion of cationic starch in pulp and paper millsystems.

Another object of invention is to provide a pitch dispersing compositionwhich prevents pitch build up in paper mill systems.

Another object of invention is to provide pitch dispersing compositionwhich is useable with uncooked cationic water dispersible starches.

Yet another object of invention is to provide a pitch dispersingcomposition which effectively purges paper mill systems.

Yet additional objects of invention will become apparent from theensuing specification.

3,l2,h5 Patented Aug. 27, lSGB Pitch as it occurs in pulp and papermills behaves as a negatively charged, hydrophobic colloid. Chemically,pitch conslsts primarily of a mixture of fatty acids and rosin acids,the former being largely combined with glycerine in the form of esters.The fatty "acids, primarily oleic and linoleic, are subject to oxidationwith a resulting change in tackiness. The rosin acids are of two types:the abietic acids which are subject to oxidation and the pimaric acidswhich are not subject to oxidation, as a result of having non-conjugateddouble bonds; here too oxidation results in a change in tackiness. Inmost pitches small amounts of waxes (esters of higher alcohols) areprobably present.

Repeated experimentation has shown that pitch taken from wounds onspruce, pine and other conifers only partially resembles the materialcausing trouble in pulp and paper mills. There is considerabledisagreement as to the best way to isolate pitch for scientific study inthe laboratory because of the tendency of the isolated material tobehave in a manner different from pitch which occurs in mill operations.

As hereinbefore stated, pitch troubles depend upon the kind of pulp usedand may depend, as well, upon any of the following known contributingfactors:

(a) Presence of calcium and magnesium ions in the mill process water,which ions react with the pitch acid to give insoluble, sticky deposits.

(b) Beating of pulp in order to develop hydration and strength mayresult in the entrapment of pitch in the crushed fiber.

(0) Hard sizing by means of rosin size and alum may aggravate the pitchproblem since the rosin contains abietic acids, itself, and as pointedout below, alum creates special problems.

(d) Foaming by means of air and CO resulting in the accumulation ofcolloidal particles of pitch in the foam.

(2) Variation in pH. Around pH 6 or 7 pitch is not readily dispersed bywater and may float to the surface or precipitate to the bottom of thereaction vessel. At higher and lower pH dispersion :occurs more readily.

(f) The use of green or unseasoned wood, the use of alum in low pHranges, increased temperatures, reuse of water in the mill systems andthe use of a high percentage of virgin sulfite pulp, particularly intissue mill opera tions, all may result in pitch buildup in the systemand the formation of pitch deposits.

The suggested composition and ranges are:

Percent Cationic starch, cold water soluble 25 to Glycerolmonostearate 5to 15 Nonylphenol polyethylene glycol other (non ionic surface activeagent) O to 5 Deodorized kerosene 20 to 50 Currently availablecommercial types of the foregoing ingredients are as follows:

Cationic starchCato CWS Starch Glycerol monostearate-Aldo 33 Nonylphenolpolyethylene glycol etherNeutronyx 622 (or equivalent with 4 to 6 (OCHCH groups) Deodorized kerosene-Bayol D 3 and the agitation in heaters orhydropulpers is always strong.

(2) Pitch dispersing composition is dispersed in warm 'or hot water toform a 3 to dispersion, which is metered into the pulp-Normally, andespecially in ground Wood, the present pitch dispersing composition maybe added at the rate of 2 ounces per ton; however, extreme conditionsmay require use rate as high as pounds per ton. Multipoint addition ispracticed where pitch agglomerates are detected at more than onelocation in the mill system. The pitch dispersing composition should beadded just ahead of each trouble point, when a single point addition inthe system fails to accomplish the job.

Although experimentation is not yet complete a suggested possible effectof thepresent composition is that it serves to peptize the negativelycharged colloid which is pitch. The peptized colloid remains dispersed,that is it does not form agglomerates, and under favorable circumstancesis carried out in the finished paper, but in particles so small as to dono harm. Paper thus has a higher pitch content when made with the pitchdispersing composition than when made Without i Manifestly, proportionsof ingredients in the present composition may be varied and the methodof application of the composition may be varied Without departing fromthe spirit and scope of invention as defined in the subjoined claims.

I claim:

1. A method for dispersing pitch within pulp comprising dissolving inwater a solution consisting of cationic starch 25 to 75%, glycerolmonostearate 5 to and kerosene to 50% and adding said solution to saidpulp at the rate of 2 ounces to 10 pounds of said starch, glycerolmonostearate and kerosene per ton of pulp.

2. The method according to claim 1, wherein said solution is multi-pointadded to a moving stream of said pulp.

3. A method for dispersing pitch Within pulp comprising dissolving inWater a solution consisting of cationic starch to 75%, glycerolmonostearate 5 to 15%, nonylphenol polyethylene glycol ether 0.1 to 5%and deodorized kerosene 20 to 50%, and adding said solution to said pulpat the rate of 2 ounces to 10 pounds of said starch, glycerolmonostearate and kerosene per ton of pulp.

4. A method for dispersing pitch Within pulp comprising stronglyagitating said pulp and adding to said pulp at the rate of 2 ounces to10 pounds per ton of pulp a composition comprising water solublecationic starch 25 to 75%, glycerol monostearate 5 to 15%, nonylphenolpolyethylene glycol ether 0.1 to 5% and kerosene 20 to 5 5. The methodaccording to claim 4, including maintaining said pulp at a consistencyin excess of 4%.

6. A method for dispersing pitch within pulp compris ing maintainingsaid pulp at 4% consistency, agitating said pulp and directly adding tosaid pulp a solid composition at the rate of two ounces to 10 lbs. ofcomposition per ton of pulp, said composition consisting 25 to 75%,glycerol monostearate '5 to 15 a non-ionic surface active agent 0.1 to5% and deodorized kerosene 20 to 50%.

7. A pitch dispersing composition comprising cationic starch 25 to 75%,glycerol monostearate 5 to 15% and kerosene 20 to 5 0%.

8. A pitch dispersing composition comprising cationic starch in therange 25 to 75 glycerol monostearate in the range 5 to 15 nonylphenolpolyethylene glycol ether in the range .01 to 5% and kerosene in therange 9. A pitch dispersing composition comprising cold water solublecationic starch 50%, glycerol monostearate 9.1%, nonlyphenolpolyethylene glycol ether .9% and kerosene 10. A pitch dispersingcomposition as in claim 9', Wherein said kerosene is deodorized. 4

11. The method according to claim 4, wherein said kerosene isdeodorized.

References Cited in the file of this patent UNITED STATES PATENTS CanadaDec. 2, 1958 of cationic starch V W

1. THE METHOD FOR DISPERSING PITCH WITHIN PULP COMPRISING DISSOLVING INWATER A SOLUTION CONSISTING OF CATIONIC STARCH 25 TO 75%, GLYCEROLMONOSTREARATE 5 TO 15% AND KEROSENE 20 TO 50% AND ADDING SAID SOLUTIONTO SAID PULP AT THE RATE OF 2 OUNCES TO 10 POUNDS OF SAID STARCH,GLYCEROL MONOSTREARATE AND KEROSENE PER TON OF PULP.